Various methods of drug administration are known in the art, including hypodermic delivery, oral delivery and nasal delivery. Hypodermic delivery of drugs is disadvantageous in that it can cause localized damage to arteries from repeated injections, create highly concentrated doses of drugs in tissues before the drugs are distributed by the circulatory system, and increase the probability of infection from hypodermic use. Oral administration of drugs is advantageous in patient convenience, and therefore increases the probability of patient compliance. Nasal and pulmonary drug delivery methods and apparatus are advantageous owing to low patient discomfort, rapid drug absorption, reduced degradation of drug compounds by the gastrointestinal system and reduced systemic side effects resulting from the drugs.
Conventional oral and nasal drug delivery methods and apparatus often employ aerosol formulations. For example, the Cook et al U.S. Pat. Nos. 4,044,126, 4,414,209 and 4,364,923 relate to the use of aerosol formulations for the adminstration of anti-inflammatory steroids. The Cook et al patents disclose a method for preparing the steroid in a crystalline form for use in the aerosol formulations. The Tom et al publication entitled "Particle Formation with Supercritical Fluids-A Review", Journal of Aerosol Science, Volume 22, No. 5, pages 555-584 (1991), discloses the use of supercritical solutions to form particles for use in aerosol formulations. The Smith U.S. Pat. No. 4,582,731 and the Sievers et al U.S. Pat. No. 4,970,093 further disclose the use of supercritical fluids for powder and film formation, but do not relate particularly to powders or films of medicaments or drugs. The use of supercritical fluid solutions to form precipitates of various metal salts was first disclosed by Hannay et al, Chem. News, 40,256 (1879).
It is also known to administer powdered medicaments orally or nasally. The Hallworth et al U.S. Pat. Nos. 4,206,758 and 4,353,365 disclose inhalation devices by which powdered medicaments can be orally or nasally inhaled by a patient through a nozzle. The Newell et al U.S. Pat. Nos. 4,627,432 and 4,811,731 disclose additional inhalation devices for administering medicaments in finely divided solid form or in fluid form.
Owing to the advantages of oral and nasal drug delivery as discussed above, a continuing need exists for additional methods and apparatus for successful oral and nasal drug delivery.